In the past, the general approach to controlling objectional engine noise has been to force exhaust gases through a series of baffles designed to convert acoustic energy to mechanical work, and to employ a lengthy system of pipes designed to vent polluted gases at the rear of the vehicle. Both of these systems, however, produce positive back-pressure at the exhaust port of the cylinders. This back-pressure not only tends to impede post ignition purging of gases during the exhaust cycle, but also tends to leave a residue that limits complete charging of engine cylinders with combustion mixture on the intake cycle.
Further, in recent years at considerable cost to the public in a worsened fuel economy, the addition of the mandatory catalytic converters has aggravated the positive back-pressure problem. These catalytic converters may also contribute to the formation of pollutants by increasing high temperature dwell time of exhaust gases. Efforts to compensate for the effects of exhaust stream back-pressure have been made by incorporating "supercharger" devices in the carburetor system. These devices are only partially effective as they can only reduce but not reverse the back-pressure factor.
There is also a wide spread belief that heat generated in the manifold and engine block by back-pressure of the exhaust system somehow enhances combustion efficiency. However, this belief overlooks the fact that much greater heat is generated by combustion initiated in or near the center of the cylinder and spreads to the relatively cool sides. Also, it is precisely the high temperatures in the manifold produced by back-pressure of conventional exhaust systems that accelerates the formation of compounds such as NO and retards the oxidation of CO to carbon dioxide. Further, back-pressure inhibits purging of burned and unburned combustion products from the cylinder during exhaust-stroke cycle of the piston, and regardless of other engine improvements, fuel economy in conventional engines are always limited to some degree by these residual unpurged exhaust gases in the cylinder at the beginning of the intake cycle. The associated carbon particles formed from incompletely burned fuel are randomly deposited on exposed metal surfaces of the combustion chamber and are chiefly responsible for the carbon deposits and oil sludge that gradually reduce engine efficiency and increase engine wear.
Previously, exhaust systems have employed conventional muffler arrangements, and more recently air pumps, as a means for quieting, dispersing and evacuating exhaust gases. Pumps have been also employed primarily with diesel engines for evacuating exhaust gases as a means for increasing the breathing efficiency of the engine. Heretofore none of these systems have incorporated a plurality of these conventional methods into a single device.
The present invention seeks to solve some of the inefficiencies of these conventional exhaust systems when installed to replace the exhaust plumbing, mufflers and catalytic converters (if any) on internal combustion engines.
It is therefore one object of the present invention to provide an exhaust conditioning system to control unwanted exhaust heat.
It is another object of the present invention to provide an exhaust conditioning system which improves the control of unwanted exhaust noise and engine noise transmitted through the exhaust gas medium, in a configuration which can replace conventional muffler systems.
Yet another object of the present invention is to rapidly reduce exhaust gas temperatures below critical levels at which pollutants such as NO and CO are propagated, by an efficient heat exchanged system in a configuration which can replace catalytic converter systems.
Still another object of the present invention is to provide an exhaust control system which frees pistons from exhaust resistance on the expelling stroke to improve engine performance, efficiency, and fuel economy by reducing back pressure.